The present invention relates to mineral mining installations employing scraper-chain conveyors.
It is well known to use longwall scraper-chain conveyors to transport mineral, e.g. coal in a mine working and to guide a mining machine, e.g. a plough, on the conveyor.
The machine is then driven with the aid of a chain circulated along the conveyor.
The conveyor usually has frames at its ends which rotatably support drums around which the scraper-chain assembly is entrained. Drive means serves to rotate one or both of these drums and further drive means, conveniently connected to the mineral face side of one or both frames, serves to drive the chain and hence the machine. Normally the frame and drive means at the discharge end of the conveyor is termed the main drive station and the frame and drive means at the opposite end is termed the auxiliary drive station.
In such installations it is generally desirable to control the tension in the drive chain and preferably in both the drive chain and the scraper-chain assembly. In order to control the tension in the drive chain it is known, for example from German Patent Specification 2135163, to have a sprocket driving the chain mounted on a unit, such as a housing termed a sprocket-box, which is displaceable in relation to the frame at one end of the conveyor.
A general object of the present invention is to provide an improved installation of the aforementioned kind.